At the beginning of the Western Han Dynasty, on the eve of her wedding, a Chang'an singing girl named Dou Yifang met Prince Liu Heng who was persecuted by Empress Dowager Lü. She used her fiance's tiger tally to save him from the city, which resulted in her family being executed and herself being sent to the palace as a slave. She devised a plan to switch the son of Concubine Wang with the daughter of Empress Dowager Lü's granddaughter - Queen Zhang Yan. Empress Dowager Lü appreciated her intelligence and resourcefulness, so under the guise of an arranged marriage, she sent her to the Dai region to monitor Liu Heng and his mother. For the sake of the common people no longer suffering, and also for Empress Dowager Lü to trust her more, Yifang suggested that Liu Heng secretly train troops under the pretense of building a palace, making everyone think she was a source of trouble.